There have been a number of studies suggesting the efficacy of spinal manipulation, the signature therapy of chiropractic (DC) care, for chronic headache (HA). Yet, there have been no large trials to determine optimal care in terms of the number of treatments, frequency of office visits, or duration of care. As a first step, we conducted a small randomized trial (n = 24) to make a preliminary evaluation of the effect on headache outcomes of the number of treatments in a fixed time period. The trial suggested important reduction of pain, disability, and number of headaches with a larger number of treatments. We thus propose a rigorously designed pilot study to assess the feasibility and inform the design of an R01 application for the first large-scale trial on the number of DC treatments for the care of chronic HA. The long-range goals are to inform evidence-based treatment protocols, third-party payer reimbursement, and schedules of chiropractic care used in future trials. We will study cervicogenic HA, HA related to neck pain and dysfunction. [unreadable] [unreadable] Our pilot will be innovative in that it will investigate both dose-response and efficacy of manipulation performed by DCs for the care of headache, as well as control attention bias and patient expectation. A total of 80 participants will be randomized to 4 treatment groups (n = 20/group). They will be randomized to dose (8 or 16 treatments) and to therapy (spinal manipulation or light massage control). Light massage, provided by a massage therapist, will serve as the comparison therapy for efficacy assessment. To control attention (including sympathy and the laying on of hands), all participants will have 16 visits (2/wk for 8 wk); those receiving only 8 treatments will also receive 8 visits for functional assessment and a sympathetic ear. [unreadable] [unreadable] Principal outcomes will be HA pain, disability and frequency evaluated at 12 and 24 weeks after randomization. The primary outcome will be HA pain at 12 weeks. [unreadable] [unreadable] There are two specific aims. The first is to acquire information for designing a large clinical trial and determine its feasibility. The second is to estimate dose and efficacy parameters for a larger study for determining the relationship of cervicogenic headache outcomes with the number of treatments. [unreadable] [unreadable]